ST. ANTHONY, Idaho  A multiple-year study of wolverines by the Wildlife Conservation Society and state and federal agencies has found that the fierce, reclusive animals travel hundreds of miles.

"The most striking thing we've found, putting GPS collars on, is just how far they travel," Jeff Burrell, Greater Yellowstone program manager for the society, told The Associated Press on Thursday. "They are amazing little travelers."

The study, which began in 2000 and is set to go at least through 2008, also turned up two of the six reproductive den sites documented in the lower 48 states, including one in Idaho's Caribou Targhee National Forest. The study area includes eastern Idaho and much of western Montana and Wyoming.

The goal of the research is to get an idea of the number of wolverines in the area, identify wildlife travel corridors, learn how wolverines are affected by such recreation activities as snowmobiling and backcountry skiing and make management recommendations about habitat and wolverine populations.

"The main issue with wolverines is winter snow-machine use," Mark Orme, a wildlife biologist with the Targhee National Forest, told the Rexburg Standard Journal. "But so far, no scientific study shows an effect one way or the other."

At 17 to 40 pounds, wolverines are the largest member of the weasel family. Two efforts to have them listed for protection under the Endangered Species Act have failed, partly because not enough information is available about the secretive animal.

The current study aims to fill in some of the information gaps.

"We wanted a longer-term study so we could follow their life cycles, how successfully they reproduced, and then follow their offspring," Burrell said.

Twenty-six wolverines have been captured, 15 females and 11 males. All were fitted with radio transmitters and a handful of the males also received GPS units. Nine of them have died.

"Our study was the first to put GPS collars on wolverines to understand how they travel around the Yellowstone region," Burrell said.

The study tracked one male wolverine from February 2001, when it was 11 months old, to its death in a trap on Jan. 11, 2004.

That wolverine had a territory of more than 14,000 square miles, moving from Grand Teton National Park in Wyoming to the Portneuf Range east of Pocatello and then back to the Teton Range, covering about 250 miles in 19 days, according to the study.

The animal was eventually trapped and killed in Montana, where such trapping is legal. Trapping wolverines is prohibited in Idaho and Wyoming, Orme said.

Two of the 26 collared wolverines were killed by predators, one by an avalanche and one by unknown means. Four died in traps and one was killed on a road.

Burrell said wolverines spend most of their time at higher elevations, only entering valleys during their travels from one place to another.

He said the study has not found any interaction between wolverines and wolves, though wolverines have confronted black bears and grizzly bears. Burrell said wolverines have been killed by bears but have also successfully driven grizzly bears off a carcass.

"When it comes to food they know no fear," Burrell said. "They will take on any competitor, as big as they come."